A model for the consolidation of warp-knitted reinforced laminates

A model for the consolidation of thermoplastic composites reinforced with a warpknitted fabric was developed. The evolution of void content during composite consolidation achieved via film stacking was related to the processing parameters and the material properties. Since the knitting process results in local variations of fiber volume fractions even within a tow, the flow mechanisms are not identical to those occurring in homogeneously dispersed fibers. Two different types of micro-scale porosities were determined and a unit cell geometry was proposed for modeling. The reduction of the effective pressure due to the gas entrapment was also accounted for. Predictions of the variation of the void content as a function of time, pressure and temperature were compared to experimental data. As a good correlation was found between experiments and predictions, this approach can thus be applied to the consolidation of textile reinforcements in which the tows are locally compressed.